Where can I mail a fan letter to Michael J Fox?

try one of these:

c/o The Michael J. Fox Foundation For Parkinson's
Grand Central Station
PO Box 4777
New York, NY 10163
USA

Michael J. Fox
25 Quogue Street
Quogue, NY 11959
USA

Michael J. Fox
Hyperion Editorial Department
77 West 66th Street
11th Floor
New York, NY 10023
USA

Michael J. Fox
7 Peabody Ct
Teaneck, NJ 07666
USA

there's actually seven of them, but the others i think are outdated. these are the most recent adresses.